Transmission device

ABSTRACT

A phase/amplitude control section controls the phase and amplitude of at least one of the signals: a distributed signal distributed by a modulation signal distributor and a reference signal based on an orthogonal base-band signal. A signal combiner combines a combinatory signal according to the distributed signal and the reference signal whose phase and amplitude have been controlled. A reference table updating section updates non-linear distortion compensating data according to the combinatory signal subjected to A/D conversion and the orthogonal base-band signal. With this configuration, since a known signal component is removed from the combinatory signal, the change amount of the signal input to the A/D converter of a feedback system circuit is reduced and the A/D converter of the feedback system circuit need not have a wide dynamic range performance.

TECHNICAL FIELD

The present invention relates to a transmission devices to be used in acommunication apparatus of a radio communication system adopting adigital modulation method, the transmission device compensatesnon-linear distortion created in an amplifier of a transmission system.

BACKGROUND ART

Mobile communication systems adopting a digital modulation method havebeen actively developed in recent years. Use of a more efficientamplifier in a transmission system in order to save power at radioterminals tends to invite more non-linear distortions, which should bethus compensated.

One of the methods of compensating the non-linear distortions uses avalue of transmission base-band signal for referring to a distortioncompensation table, thereby compensating non-linear distortions both inamplitude and phase. In this method, feedback of parts of transmissionsignals and update of the distortion compensation table allow thecompensation to follow the changes in characteristics of the amplifier.

The foregoing instanced transmission device orthogonally demodulates afeedback signal, and a resultant signal undergoes an analog-digital(A/D) conversion to form a digital feedback signal, which is thencompared with orthogonal-modulation signal to be transmitted, therebyupdating the distortion compensation table. This transmission device isdisclosed in Japanese Patent Non-Examined Application Publication No.H06-37831.

A conventional transmission device as discussed above feeds back asignal including an output modulation signal to be supplied outside anda non-linear distortion component created in transmission systemcircuits, so that an A/D converter of a feedback system circuit needs tohave wide dynamic range performance.

DISCLOSURE OF INVENTION

The present invention aims to provide a transmission device having afunction of compensating non-linear distortions, and yet, the A/Dconverter in the feedback system circuit needs not to have wide dynamicrange performance.

The transmission device of the present invention comprises the followingelements:

-   -   a non-linear distortion compensating section,    -   a first orthogonal modulator,    -   a modulation signal distributor,    -   a phase/amplitude control section,    -   a signal combiner, and    -   a reference table updating section.        The non-linear distortion compensating section uses non-linear        distortion compensating data for compensating non-linear        distortions, and compensates the non-linear distortions of        orthogonal base-band signals digitally demodulated. The first        orthogonal modulator orthogonally modulates the orthogonal        base-band signals undergone the non-linear distortion        compensation. The modulation signal distributor distributes        modulation signals amplified from the signals undergone the        first orthogonal modulator. The phase and amplitude controller        controls both of the phase and amplitude of at least one of the        signals distributed by the modulation signal distributor and a        reference signal based on the orthogonal base-band signal. The        signal combiner forms combinatory signals based on the        distributed signals and the reference signal at least one of        which phase and amplitude are controlled by the phase/amplitude        control section. The reference table updating section updates        non-linear distortion compensating data based on the orthogonal        base-band signal and the combinatory signals undergone the A/D        conversion.

The foregoing structure allows eliminating a known signal component bycombining the combinatory signal based on the signals distributed fromthe modulation signals and the reference signal. Thus a change amount ofa signal fed into A/D converter of the feedback system circuit becomessmaller, so that the A/D converter need not a wide dynamic range.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a block diagram illustrating a structure of a transmissiondevice specifically in accordance with a first exemplary embodiment ofthe present invention.

FIG. 2 shows a block diagram illustrating a structure of a transmissiondevice specifically in accordance with a second exemplary embodiment ofthe present invention.

FIG. 3 shows a block diagram illustrating a structure of a transmissiondevice specifically in accordance with a third exemplary embodiment ofthe present invention.

FIG. 4 shows a block diagram illustrating a structure of a transmissiondevice specifically in accordance with a fourth exemplary embodiment ofthe present invention.

FIG. 5 shows a block diagram illustrating a structure of a transmissiondevice specifically in accordance with a fifth exemplary embodiment ofthe present invention.

FIG. 6 shows a block diagram illustrating a structure of a transmissiondevice specifically in accordance with a sixth exemplary embodiment ofthe present invention.

FIG. 7 shows a block diagram illustrating a structure of a transmissiondevice specifically in accordance with a seventh exemplary embodiment ofthe present invention.

FIG. 8 shows a block diagram illustrating a structure of a transmissiondevice specifically in accordance with an eighth exemplary embodiment ofthe present invention.

FIG. 9 shows a block diagram illustrating a structure of a transmissiondevice specifically in accordance with a ninth exemplary embodiment ofthe present invention.

FIG. 10 shows a block diagram illustrating a structure of a transmissiondevice specifically in accordance with a tenth exemplary embodiment ofthe present invention.

BEST MODE FOR PRACTICING THE INVENTION

The inventor of the present invention finds the following fact, whichleads the present invention: In a transmission device adopting anon-linear distortion compensating method which feeds back parts of atransmission signal, direct transform of the transmission signal into afeedback signal produces a great difference between a level of thetransmission signal component and a level of unnecessary component to beeliminated. Thus an A/D converter of a feedback system circuit needs awide dynamic range. However, if the transmission signal component is notfed back, the dynamic range required to the A/D converter can benarrowed.

In other words, the gist of the present invention is to combine atransmission signal and a reference signal, and eliminate the referencesignal component from a feedback signal, so that an A/D converter of afeedback system circuit needs not to have wide dynamic rangeperformance.

Exemplary embodiments of the present invention are demonstratedhereinafter with reference to the accompanying drawings.

Exemplary Embodiment 1

FIG. 1 shows a block diagram illustrating a structure of a transmissiondevice in accordance with the first exemplary embodiment of the presentinvention. The transmission device shown in FIG. 1 comprises thefollowing elements:

-   -   non-linear distortion compensating section 102 for calculating        instantaneous power 103 of transmission digital orthogonal        base-band signal 101;    -   compensation coefficient referencing section 104 for referencing        to data for compensating non-linear distortions;    -   reference table 106 for outputting non-linear distortion        compensating data 107 corresponding to reference address 105        shown by compensation coefficient referencing section 104;    -   instantaneous power calculator 109 for providing transmission        digital orthogonal base-band signal 101 with non-linear        distortion compensation by using orthogonal non-linear        distortion compensating data 108 supplied from compensation        coefficient referencing section 104;    -   first orthogonal modulator 111 for orthogonally modulating        orthogonal base-band signal 110 undergone the non-linear        distortion compensation;    -   power amplifier 113 for amplifying the power of modulation        signal 112 undergone the orthogonal modulation;    -   directional coupler 115 for outputting amplified transmission        modulation signal 114 as output modulation signal 116 as well as        distributing parts of power as transmission modulation signal        117;    -   phase/amplitude control section 118 for controlling the phase        and amplitude of transmission modulation signal 117;    -   directional coupler 120 for combining feedback signal 125 based        on transmission modulation signal 119 whose phase and amplitude        are controlled;    -   second data delaying section 121 for producing transmission        digital orthogonal base-band signal 122 delayed from and based        on transmission digital orthogonal base-band signal 101;    -   second orthogonal modulator 123 for orthogonally modulating        delayed transmission digital orthogonal base-band signal 122,        providing signal 122 with D/A conversion to produce reference        modulation signal 124 which is a reference signal to the        feedback signal;    -   orthogonal demodulator 126 for providing feedback signal 125        with A/D conversion before orthogonally demodulating signal 125;    -   reference signal updating section 128 for updating a reference        table based on demodulated feedback digital orthogonal base-band        signal 127; and    -   first data delaying section 129 for producing delayed        transmission digital orthogonal base-band signal 130 to be used        for updating the reference table.

An operation of the transmission device having the foregoing structureis demonstrated hereinafter. Non-linear distortion compensating section102 calculates an amount of instantaneous power of a transmission signalbased on transmission digital orthogonal base-band signal 101.Compensation coefficient referencing section 104 produces referenceaddress 105 based on the amount of the instantaneous power of thetransmission signal, and refers to reference table 106 to be used forcompensating non-linear distortions, thereby obtaining non-lineardistortion compensating data 107 having reversal characteristics tothose of non-linear distortion of the transmission system, and finallyoutputs orthogonal non-linear distortion compensating data.

Instantaneous power calculator 109 produces a complex product ofbase-band signal 101 and non-linear distortion compensating data 108,and outputs orthogonal base-band signal 110 undergone the non-lineardistortion compensation. First orthogonal modulator 111 orthogonallymodulates compensated base-band signal 110, then provides signal 110with D/A conversion, and outputs analog modulated signal 112.

Power amplifier 113 amplifies analog modulated signal 112 up to anecessary value, and outputs transmission modulation signal 114.Directional coupler 115 outputs the most parts of signal 114 asoutput-transmission modulation signal 116, and distributes the rest astransmission modulation signal 117.

Phase/amplitude control section 118 controls the phase and amplitude ofdistributed transmission modulation signal 117 such that a desirablesignal component of signal 117 has an amplitude equal to that ofreference modulation signal 124 created in second orthogonal modulator123 and has a phase different by 180° from that of signal 124. Thencontrol section 118 outputs controlled signal 119.

Second data delaying section 121 delays transmission digital orthogonalbase-band signal 101 by a predetermined amount. Second orthogonalmodulator 123 orthogonally modulates digital transmission orthogonalbase-band signal 122 delayed by second data delaying section 121, andprovides signal 122 with D/A conversion to produce reference modulationsignal 124.

Directional coupler 120 combines signal 119, whose phase and amplitudeare controlled, with reference modulation signal 124, then outputsfeedback signal 125. Orthogonal demodulator 126 provides feedback signal125 with A/D conversion before orthogonally demodulating the signal 125,then outputs feedback digital orthogonal base-band signal 127.

First data delaying section 129 delays transmission digital orthogonalbase-band signal 101 by a delayed time of the feedback system circuit,and outputs delayed transmission digital orthogonal base-band signal130. Reference table updating section 128 updates reference table 106with non-linear distortion compensating data 131 based on delayedtransmission digital orthogonal base-band signal 130 and feedbackdigital orthogonal base-band signal 127.

As discussed above, this embodiment shows that the control of a feedbacksignal, i.e. the distributed transmission modulation signal, such thattransmission modulation signal 119 and reference modulation signal 124have an amplitude equal to each other and a phase difference in 180degrees from each other, thereby removing a known component of thereference modulation signal. This preparation allows reducing a changeamount of an input signal at A/D conversion in the feedback systemcircuit. As a result, the A/D converter of the feedback system circuitdoes not necessarily to have a wide dynamic range performance. Use of areference table in this first embodiment allows compensatingappropriately distortions created in a transmission system circuit, suchas a power amplifier, having non-linear characteristics which is hard toexpress in a numerical formula.

Exemplary Embodiment 2

A transmission device in accordance with the second exemplary embodimentof the present invention obtains non-linear distortion compensating datanot from reference table 106 but from calculation with computingequations prepared in compensation coefficient calculator 204. Thecoefficients of the computing equations are updated based on thefeedback digital orthogonal base-band signal. The second embodiment isdemonstrated hereinafter, but the descriptions of the same sections asthose of the first embodiment are omitted, and the different sectionsfrom the first embodiment are focused.

FIG. 2 shows a block diagram of the transmission device in accordancewith the second embodiment. This transmission device comprises thefollowing elements:

-   -   instantaneous power calculator 202;    -   compensation coefficient calculator 204 for calculating data to        be used to compensate non-linear distortions;    -   non-linear distortion compensating section 206;    -   first orthogonal modulator 208;    -   power amplifier 210;    -   directional coupler 212;    -   phase/amplifier control section 215;    -   directional coupler 217;    -   second orthogonal modulator 220;    -   orthogonal demodulator 223;    -   computation coefficient updating section 225;    -   first data delaying section 226; and    -   second data delaying section 218.

An operation of the transmission device as structured above isdemonstrated hereinafter. Instantaneous power calculator 202 calculatesa magnitude of transmission signal 203 based on transmission digitalorthogonal base-band signal 201. Compensation coefficient calculator 204calculates orthogonal non-linear distortion compensating data 205 by apredetermined computing equation based on the magnitude of transmissionsignal 203.

Non-linear distortion compensating section 206 produces a complexproduct of base-band signal 201 and non-linear distortion compensatingdata 205, and outputs orthogonal base-band signal 207 undergone thenon-linear distortion compensation. First orthogonal modulator 208orthogonally modulates compensated base-band signal 207, then providessignal 207 with D/A conversion, and outputs analog modulated signal 209.

Power amplifier 210 amplifies analog modulated signal 209 up to anecessary value, and outputs transmission modulation signal 211.Directional coupler 212 outputs the most parts of signal 211 asoutput-transmission modulation signal 213, and distributes the rest astransmission modulation signal 214. Phase/amplitude control section 215controls the phase and amplitude of distributed transmission modulationsignal 214 such that a desirable signal component of signal 214 has anamplitude equal to that of reference modulation signal 221 created insecond orthogonal modulator 220 and has a phase different by 180° fromthat of signal 221. Then control section 215 outputs controlled signal216.

Second data delaying section 218 delays transmission digital orthogonalbase-band signal 201 by a predetermined amount. Second orthogonalmodulator 220 orthogonally modulates digital transmission orthogonalbase-band signal 219 delayed by second data delaying section 218, andprovides signal 219 with D/A conversion to produce reference modulationsignal 221. Directional coupler 217 combines signal 216, whose phase andamplitude are controlled, with reference modulation signal 221, thenoutputs feedback signal 222.

Orthogonal demodulator 223 provides feedback signal 222 with A/Dconversion before orthogonally demodulating the signal 222, then outputsfeedback digital orthogonal base-band signal 224.

First data delaying section 226 delays transmission digital orthogonalbase-band signal 201 by a delayed time of the feedback system circuit,and outputs delayed transmission digital orthogonal base-band signal227. Computation coefficient updating section 225 updates coefficient228 of the computing equation, by which compensation coefficientcalculator 204 calculates the non-linear distortion compensating data,based on delayed transmission digital orthogonal base-band signal 227and feedback digital orthogonal base-band signal 224.

As discussed above, this embodiment shows that the control of a feedbacksignal, transmission modulation signal, such that transmissionmodulation signal 216 and reference modulation signal 221 have anamplitude equal to each other and a phase difference in 180 degrees fromeach other. Then coupler 217 removes a known component of referencemodulation signal 221. This preparation allows reducing a change amountof an input signal at A/D conversion in the feedback system circuit. Asa result, the A/D converter of the feedback system circuit does notnecessarily to have wide dynamic range performance.

Use of an approximate equation to express non-linear characteristics inthis second embodiment allows obtaining non-linear distortioncompensating data with a little amount of memory, and therebycompensating appropriately distortions created in a transmission systemcircuit, such as a power amplifier.

In the foregoing demonstration, the non-linear distortion compensatingdata is found by a computing equation; however, the data is not limitedto a specific one as long as the data can be found by processing digitalsignals. For instance, the coefficient can be changed by combiningcomputing equations based on a fixed reference table.

An instantaneous power of the transmission digital orthogonal base-bandsignal is used as an input for finding the non-linear distortioncompensating data; however, the present invention is not limited to thisinput. For instance, an instantaneous amplitude of the foregoing signalor the square of an instantaneous power of the same signal can be used.

Exemplary Embodiment 3

The transmission device in accordance with the third exemplaryembodiment of the present invention changes an input of aphase/amplitude controller sourcing from an output supplied from secondorthogonal modulator 321 instead of sourcing from an output suppliedfrom directional coupler 115. The third embodiment is demonstratedhereinafter, but the descriptions of the same sections as those of thefirst embodiment are omitted, and the different sections from the firstembodiment are focused.

FIG. 3 shows a block diagram illustrating the transmission device inaccordance with the third embodiment. This transmission devicecomprising the following elements:

-   -   instantaneous power calculator 302;    -   compensation coefficient referencing section 304;    -   reference table 306;    -   non-linear distortion compensating section 309;    -   first orthogonal modulator 311;    -   power amplifier 313;    -   directional couplers 315, 318;    -   second data delaying section 319;    -   second orthogonal modulator 321;    -   phase/amplifier control section 323;    -   orthogonal demodulator 326;    -   directional coupler 217;    -   reference table updating section 328; and    -   first data delaying section 329.

An operation of the transmission device as structured above isdemonstrated hereinafter. Instantaneous power calculator 302 calculatesa magnitude of transmission signal 303 based on transmission digitalorthogonal base-band signal 301. Compensation coefficient referencingsection 304 produces reference address 305 based on the magnitude oftransmission signal 303, then refers to reference table 306 to be usedfor compensating non-linear distortion, thereby obtaining non-lineardistortion compensating data 307 having characteristics reversal to thenon-linear characteristics of the transmission system for outputtingorthogonal non-linear distortion compensating data 308.

Non-linear distortion compensating section 309 produces a complexproduct of base-band signal 301 and orthogonal non-linear distortioncompensating data 308, and outputs orthogonal base-band signal 310undergone the non-linear distortion compensation. First orthogonalmodulator 311 orthogonally modulates compensated base-band signal 310,then provides signal 310 with D/A conversion, and outputs analogmodulated signal 312.

Power amplifier 313 amplifies analog modulated signal 312 up to anecessary value, and outputs transmission modulation signal 314.Directional coupler 315 outputs the most parts of signal 314 asoutput-transmission modulation signal 316, and distributes the rest astransmission modulation signal 317.

Second data delaying section 319 delays transmission digital orthogonalbase-band signal 301 by a predetermined amount. Second orthogonalmodulator 321 orthogonally modulates digital transmission orthogonalbase-band signal 320 delayed by second data delaying section 319, andprovides signal 320 with D/A conversion to produce reference modulationsignal 322.

Phase/amplitude control section 323 controls the phase and amplitude ofreference modulation signal 322 such that signal 322 has an amplitudeequal to that of a desirable signal component of transmission modulationsignal 317 and has a phase different by 180° from that of the desirablesignal component of signal 317. Then control section 323 outputscontrolled reference modulation signal 324. Directional coupler 318combines signal 324, whose phase and amplitude are controlled, withtransmission modulation signal 317, then outputs feedback signal 325.

Orthogonal demodulator 326 provides feedback signal 325 with A/Dconversion before orthogonally demodulating the signal 325, then outputsfeedback digital orthogonal base-band signal 327.

First data delaying section 329 delays transmission digital orthogonalbase-band signal 301 by a delayed time of the feedback system circuit,and outputs delayed transmission digital orthogonal base-band signal330. Reference table updating section 328 updates reference table 306 bynon-linear distortion compensating data 331 based on delayedtransmission digital orthogonal base-band signal 330 and feedbackdigital orthogonal base-band signal 327.

As discussed above, this embodiment shows that the control of a feedbacksignal, i.e. the distributed transmission modulation signal, such thattransmission modulation signal 317 and reference modulation signal 324have an amplitude equal to each other and a phase different from eachother. Then coupler 318 removes a known component of referencemodulation signal 324. This preparation allows reducing a change amountof an input signal at A/D conversion in the feedback system circuit. Asa result, the A/D converter of the feedback system circuit does notnecessarily to have a wide dynamic range performance.

Use of a reference table in this third embodiment allows compensatingappropriately distortions created in a transmission system circuit, suchas a power amplifier, having non-linear characteristics which is hard toexpress in a numerical formula.

Exemplary Embodiment 4

The transmission device in accordance with the fourth exemplaryembodiment of the present invention changes an input of aphase/amplitude controller sourcing from an output supplied from secondorthogonal modulator 418 instead of sourcing from an output suppliedfrom directional coupler 212. The fourth embodiment is demonstratedhereinafter, but the descriptions of the same sections as those of thesecond embodiment are omitted, and the different sections from thesecond embodiment are focused.

FIG. 4 shows a block diagram of the transmission device in accordancewith the fourth embodiment. This transmission device comprises thefollowing elements:

-   -   instantaneous power calculator 402;    -   compensation coefficient calculator 404;    -   non-linear distortion compensating section 406;    -   first orthogonal modulator 408;    -   power amplifier 410;    -   directional couplers 412, 415;    -   second data delaying section 416;    -   second orthogonal modulator 418;    -   phase/amplifier control section 420;    -   orthogonal demodulator 423;    -   computation coefficient updating section 415; and    -   first data delaying section 426.

An operation of the transmission device as structured above isdemonstrated hereinafter. Instantaneous power calculator 402 calculatesa magnitude of transmission signal 403 based on transmission digitalorthogonal base-band signal 401. Compensation coefficient calculator 404calculates orthogonal non-linear distortion compensating data 405 by apredetermined computing equation based on the magnitude of transmissionsignal 403.

Non-linear distortion compensating section 406 produces a complexproduct of transmission digital orthogonal base-band signal 401 andnon-linear distortion compensating data 405, and outputs orthogonalbase-band signal 407 undergone the non-linear distortion compensation.First orthogonal modulator 408 orthogonally modulates compensatedbase-band signal 407, then provides signal 407 with D/A conversion, andoutputs analog modulated signal 409.

Power amplifier 410 amplifies analog modulated signal 409 up to anecessary value, and outputs transmission modulation signal 411.Directional coupler 412 outputs the most parts of signal 411 asoutput-transmission modulation signal 413, and distributes the rest astransmission modulation signal 414.

Second data delaying section 416 delays transmission digital orthogonalbase-band signal 401 by a predetermined amount. Second orthogonalmodulator 418 orthogonally modulates digital transmission orthogonalbase-band signal 417 delayed by second data delaying section 416, andprovides signal 417 with D/A conversion to produce reference modulationsignal 419.

Phase/amplitude control section 420 controls the phase and amplitude ofreference modulation signal 419 such that signal 419 has an amplitudeequal to that of a desirable signal component of transmission modulationsignal 414 and has a phase different by 180° from that of the desirablesignal component of signal 414. Then control section 420 outputscontrolled reference modulation signal 421. Directional coupler 415combines signal 421, whose phase and amplitude are controlled, withtransmission modulation signal 414, then outputs feedback signal 422.Orthogonal demodulator 423 provides feedback signal 422 with A/Dconversion before orthogonally demodulating the signal 422, then outputsfeedback digital orthogonal base-band signal 424.

First data delaying section 426 delays transmission digital orthogonalbase-band signal 401 by a delayed time of the feedback system circuit,and outputs delayed transmission digital orthogonal base-band signal427. Computation coefficient updating section 425 updates coefficient428 of the computing equation, by which compensation coefficientcalculator 404 calculates the non-linear distortion compensating data,based on delayed transmission digital orthogonal base-band signal 427and feedback digital orthogonal base-band signal 424.

As discussed above, this embodiment shows that the control of areference signal, i.e. the distributed transmission modulation signal,such that transmission modulation signal 414 and reference modulationsignal 421 have an amplitude equal to each other and a phase differencein 180 degrees from each other. Then coupler 415 removes a knowncomponent of reference modulation signal 421. This preparation allowsreducing a change amount of an input signal at A/D conversion in thefeedback system circuit. As a result, the A/D converter of the feedbacksystem circuit does not necessarily to have a wide dynamic rangeperformance.

Use of an approximate equation to express non-linear characteristics inthis fourth embodiment allows obtaining non-linear distortioncompensating data with a little amount of memory, and therebycompensating appropriately distortions created in a transmission systemcircuit, such as a power amplifier.

In the foregoing demonstration, the non-linear distortion compensatingdata is found by a computing equation; however, the data is not limitedto a specific one as long as the data can be found by processing digitalsignals. For instance, the coefficient can be changed by combiningcomputing equations based on a fixed reference table.

An instantaneous power of the transmission digital orthogonal base-bandsignal is used as an input for finding the non-linear distortioncompensating data; however, the present invention is not limited to thisinput. For instance, an instantaneous amplitude of the foregoing signalor the square of an instantaneous power of the same signal can be used.

Exemplary Embodiment 5

The transmission device in accordance with the fifth exemplaryembodiment of the present invention adds digital adder 528 to an outputsection of orthogonal demodulator 526. The fifth embodiment isdemonstrated hereinafter, but the descriptions of the same sections asthose of the first embodiment are omitted, and an operation focused onthe different sections from the first embodiment are detailed.

FIG. 5 shows a block diagram illustrating the transmission device inaccordance with the fifth embodiment. This transmission devicecomprising the following elements:

-   -   instantaneous power calculator 502;    -   compensation coefficient referencing section 504;    -   reference table 506;    -   non-linear distortion compensating section 509;    -   first orthogonal modulator 511;    -   power amplifier 513;    -   directional couplers 515;    -   phase/amplifier control section 518;    -   directional coupler 520;    -   second data delaying section 521;    -   second orthogonal modulator 523;    -   orthogonal demodulator 526;    -   digital adder 528;    -   third data delaying section 529;    -   reference table updating section 532; and    -   first data delaying section 533.

An operation of the transmission device as structured above isdemonstrated hereinafter. Instantaneous power calculator 502 calculatesa magnitude of transmission signal 503 based on transmission digitalorthogonal base-band signal 501. Compensation coefficient referencingsection 504 produces reference address 505 based on the magnitude oftransmission signal 503, then refers to reference table 506 to be usedfor compensating non-linear distortion, thereby obtaining non-lineardistortion compensating data 507 having characteristics reversal to thenon-linear characteristics of the transmission system. Then referencingsection 504 outputs orthogonal non-linear distortion compensating data508.

Non-linear distortion compensating section 509 produces a complexproduct of base-band signal 501 and orthogonal non-linear distortioncompensating data 508, and outputs orthogonal base-band signal 510undergone the non-linear distortion compensation. First orthogonalmodulator 511 orthogonally modulates compensated base-band signal 510,then provides signal 510 with D/A conversion, and outputs analogmodulated signal 512.

Power amplifier 513 amplifies analog modulated signal 512 up to anecessary value, and outputs transmission modulation signal 514.Directional coupler 515 outputs the most parts of signal 514 asoutput-transmission modulation signal 516, and distributes the rest astransmission modulation signal 517.

Phase/amplitude control section 518 controls the phase and amplitude ofdistributed transmission modulation signal 517 such that a desirablesignal component of signal 517 has an amplitude equal to that ofreference modulation signal 524 created in second orthogonal modulator523 and has a phase different by 180° from that of signal 524. Thencontrol section 518 outputs controlled signal 519.

Second data delaying section 521 delays transmission digital orthogonalbase-band signal 501 by a predetermined amount. Second orthogonalmodulator 523 orthogonally modulates digital transmission orthogonalbase-band signal 522 delayed by second data delaying section 521, andprovides signal 522 with D/A conversion to produce reference modulationsignal 524.

Directional coupler 520 combines signal 519, whose phase and amplitudeare controlled, with reference modulation signal 524, then outputsfeedback signal 525. Orthogonal demodulator 526 provides feedback signal525 with A/D conversion before orthogonally demodulating the signal 525,then outputs feedback digital orthogonal base-band signal 527.

Third data delaying section 529 outputs digital orthogonal base-bandsignal 530 formed by delaying signal 501 by a predetermined amount.Digital adder 528 adds signal 530 to feedback digital orthogonalbase-band signal 527, and outputs the added feedback digital orthogonalbase-band signal 531.

First data delaying section 533 delays transmission digital orthogonalbase-band signal 501 by a delayed time of the feedback system circuit,and outputs delayed transmission digital orthogonal base-band signal534. Reference table updating section 532 updates reference table 506with non-linear distortion compensating data 535 based on the delayedtransmission digital orthogonal base-band signal 534 and the addedfeedback digital orthogonal base-band signal 531.

As discussed above, this embodiment shows that the control of a feedbacksignal, i.e. the distributed transmission modulation signal, such thattransmission modulation signal 519 and reference modulation signal 524have an amplitude equal to each other and a phase difference in 180degrees from each other. Then coupler 520 removes a known component ofreference modulation signal 524. This preparation allows reducing achange amount of an input signal at A/D conversion in the feedbacksystem circuit. As a result, the A/D converter of the feedback systemcircuit does not necessarily to have a wide dynamic range performance.Use of a reference table in this fifth embodiment allows compensatingappropriately distortions created in a transmission system circuit, suchas a power amplifier, having non-linear characteristics which is hard toexpress in a numerical formula.

Further in this embodiment, since the input signal to the referencetable updating section includes a component of transmission digitalorthogonal base-band signal, no changes are needed in an algorithm usedin the reference table updating section of the conventional method. Inthe conventional method, parts of the transmission signal are fed backas a feedback signal, then the feedback signal is orthogonallydemodulated and undergoes A/D conversion to become a digital feedbacksignal. The conventional method compares this feedback signal with anorthogonal modulation signal to be transmitted.

In the foregoing description, the phase/amplitude control section isdisposed to the signal distributed from the transmission modulationsignal; however, the control section can be disposed to the referencemodulation signal instead.

Exemplary Embodiment 6

The transmission device in accordance with the sixth exemplaryembodiment of the present invention adds digital adder 625 to an outputsection of orthogonal demodulator 623. The sixth embodiment isdemonstrated hereinafter, but the descriptions of the same sections asthose of the second embodiment are omitted, and an operation focused onthe different sections from the second embodiment are detailed.

FIG. 6 shows a block diagram illustrating the transmission device inaccordance with the sixth embodiment. This transmission device comprisesthe following elements:

-   -   instantaneous power calculator 602;    -   compensation coefficient calculator 604;    -   non-linear distortion compensating section 606;    -   first orthogonal modulator 608;    -   power amplifier 610;    -   directional couplers 612;    -   phase/amplifier control section 615;    -   directional coupler 617;    -   second data delaying section 618;    -   second orthogonal modulator 620;    -   orthogonal demodulator 623;    -   digital adder 625;    -   third data delaying section 626;    -   computation coefficient updating section 629; and    -   first data delaying section 630.

An operation of the transmission device as structured above isdemonstrated hereinafter. Instantaneous power calculator 602 calculatesa magnitude of transmission signal 603 based on transmission digitalorthogonal base-band signal 601. Compensation coefficient calculator 604calculates orthogonal non-linear distortion compensating data 605 by apredetermined computing equation based on the magnitude of transmissionsignal 603.

Non-linear distortion compensating section 606 produces a complexproduct of transmission digital orthogonal base-band signal 601 andnon-linear distortion compensating data 605, and outputs orthogonalbase-band signal 607 undergone the non-linear distortion compensation.First orthogonal modulator 608 orthogonally modulates compensatedbase-band signal 607, then provides signal 607 with D/A conversion, andoutputs analog modulated signal 609.

Power amplifier 610 amplifies analog modulated signal 609 up to anecessary value, and outputs transmission modulation signal 611.Directional coupler 612 outputs the most parts of signal 611 asoutput-transmission modulation signal 613, and distributes the rest astransmission modulation signal 614.

Phase/amplitude control section 615 controls the phase and amplitude ofdistributed transmission modulation signal 614 such that a desirablesignal component of signal 614 has an amplitude equal to that ofreference modulation signal 621 created in second orthogonal modulator620 and has a phase different by 180° from that of signal 621. Thencontrol section 615 outputs controlled signal 616.

Second data delaying section 618 delays transmission digital orthogonalbase-band signal 601 by a predetermined amount. Second orthogonalmodulator 620 orthogonally modulates digital transmission orthogonalbase-band signal 619 delayed by second data delaying section 618, andprovides signal 619 with D/A conversion to output reference modulationsignal 621.

Directional coupler 617 combines signal 616, whose phase and amplitudeare controlled, with reference modulation signal 621, then outputsfeedback signal 622. Orthogonal demodulator 623 provides feedback signal622 with A/D conversion before orthogonally demodulating the signal 622,then outputs feedback digital orthogonal base-band signal 624.

Third data delaying section 626 outputs digital orthogonal base-bandsignal 627 formed by delaying the signal 601 by a predetermined amount.Digital adder 625 adds signal 627 to feedback digital orthogonalbase-band signal 624, and outputs the added feedback digital orthogonalbase-band signal 628. First data delaying section 630 delaystransmission digital orthogonal base-band signal 601 by a delayed timeof the feedback system circuit, and outputs delayed transmission digitalorthogonal base-band signal 631.

Computation coefficient updating section 629 updates coefficient 632 ofthe computing equation, by which compensation coefficient calculator 604calculates the non-linear distortion compensating data, based on delayedtransmission digital orthogonal base-band signal 631 and added feedbackdigital orthogonal base-band signal 628.

As discussed above, this embodiment shows that the control of a feedbacksignal, i.e. the distributed transmission modulation signal, such thattransmission modulation signal 616 and reference modulation signal 621have an amplitude equal to each other and a phase difference in 180degrees from each other. Then coupler 617 removes a known component fromreference modulation signal 621. This preparation allows reducing achange amount of an input signal at A/D conversion in the feedbacksystem circuit. As a result, the A/D converter of the feedback systemcircuit does not necessarily to have a wide dynamic range.

Use of an approximate equation to express non-linear characteristics inthis sixth embodiment allows obtaining non-linear distortioncompensating data with a little amount of memory, and therebycompensating appropriately distortions created in a transmission systemcircuit, such as a power amplifier.

Further in this embodiment, since input signal 628 to the referencetable updating section includes a component of transmission digitalorthogonal base-band signal, no changes are needed in an algorithm usedin the reference table updating section of the conventional method. Inthe conventional method, parts of the transmission signal are fed backas a feedback signal, then the feedback signal is orthogonallydemodulated and undergoes A/D conversion to become a digital feedbacksignal. The conventional method compares this feedback signal with anorthogonal modulation signal to be transmitted.

In the foregoing description, the phase/amplitude control section isdisposed to the signal distributed from the transmission modulationsignal; however, the control section can be disposed to the referencemodulation signal instead.

In the foregoing demonstration, the non-linear distortion compensatingdata is found by a computing equation; however, the data is not limitedto a specific one as long as the data can be found by processing digitalsignals. For instance, the coefficient can be changed by combiningcomputing equations based on a fixed reference table.

An instantaneous power of the transmission digital orthogonal base-bandsignal is used as an input for finding the non-linear distortioncompensating data; however, the present invention is not limited to thisinput. For instance, an instantaneous amplitude of the foregoing signalor the square of an instantaneous power of the same signal can be used.

Exemplary Embodiment 7

The transmission device in accordance with the seventh exemplaryembodiment of the present invention includes amplitude control section729, for controlling the amplitude of a transmission digital orthogonalbase-band signal, in addition to the transmission device of the fifthembodiment. The seventh embodiment is demonstrated hereinafter, but thedescriptions of the same sections as those of the fifth embodiment areomitted, and an operation focused on the different sections from thefifth embodiment are detailed.

FIG. 7 shows a block diagram illustrating the transmission device inaccordance with the seventh embodiment. This transmission devicecomprises the following elements:

-   -   instantaneous power calculator 702;    -   compensation coefficient referencing section 704;    -   reference table 706;    -   non-linear distortion compensating section 709;    -   first orthogonal modulator 711;    -   power amplifier 713;    -   directional couplers 715;    -   phase/amplifier control section 718;    -   directional coupler 720;    -   second data delaying section 721;    -   second orthogonal modulator 723;    -   orthogonal demodulator 726;    -   digital adder 728;    -   amplitude control section 729;    -   third data delaying section 731;    -   reference table updating section 734; and    -   first data delaying section 735.

An operation of the transmission device as structured above isdemonstrated hereinafter. Instantaneous power calculator 702 calculatesa magnitude of transmission signal 703 based on transmission digitalorthogonal base-band signal 701. Compensation coefficient referencingsection 704 produces reference address 705 based on the magnitude oftransmission signal 703, then refers to reference table 706 to be usedfor compensating non-linear distortion, thereby obtaining non-lineardistortion compensating data 707 having characteristics reversal to thenon-linear characteristics of the transmission system for outputtingorthogonal non-linear distortion compensating data 708.

Non-linear distortion compensating section 709 produces a complexproduct of base-band signal 701 and orthogonal non-linear distortioncompensating data 708, and outputs orthogonal base-band signal 710undergone the non-linear distortion compensation. First orthogonalmodulator 711 orthogonally modulates compensated base-band signal 710,then provides signal 710 with D/A conversion, and outputs analogmodulated signal 712. Power amplifier 713 amplifies analog modulatedsignal 712 up to a necessary value, and outputs transmission modulationsignal 714. Directional coupler 715 outputs the most parts of signal 714as output-transmission modulation signal 716, and distributes the restas transmission modulation signal 717.

Phase/amplitude control section 718 controls the phase and amplitude ofdistributed transmission modulation signal 717 such that a desirablesignal component of signal 717 has at least a phase different by 180°from that of reference modulation signal 724 created in secondorthogonal modulator 723. Then control section 718 outputs controlledsignal 719.

Second data delaying section 721 delays transmission digital orthogonalbase-band signal 701 by a predetermined amount. Second orthogonalmodulator 723 orthogonally modulates digital transmission orthogonalbase-band signal 722 delayed by second data delaying section 721, andprovides signal 722 with D/A conversion to produce reference modulationsignal 724. Directional coupler 720 combines signal 719, whose phase andamplitude are controlled, with reference modulation signal 724, thenoutputs feedback signal 725.

Orthogonal demodulator 726 provides feedback signal 725 with A/Dconversion before orthogonally demodulating the signal 725, then outputsfeedback digital orthogonal base-band signal 727.

Amplitude control section 729 controls an amplitude of transmissiondigital orthogonal base-band signal 701, and outputs resultant digitalorthogonal base-band signal 730. Third data delaying section 731 outputsdigital orthogonal base-band signal 732 formed by delaying signal 730 bya predetermined amount.

Digital adder 728 adds signal 732 to feedback digital orthogonalbase-band signal 727, and outputs the added feedback digital orthogonalbase-band signal 733.

First data delaying section 735 delays transmission digital orthogonalbase-band signal 701 by a delayed time of the feedback system circuit,and outputs delayed transmission digital orthogonal base-band signal736.

Reference table updating section 734 updates reference table 706 withnon-linear distortion compensating data 737 based on the delayedtransmission digital orthogonal base-band signal 736 and the addedfeedback digital orthogonal base-band signal 733.

As discussed above, this embodiment shows that the control of a feedbacksignal, i.e. the distributed transmission modulation signal, such thattransmission modulation signal 719 and reference modulation signal 724have an amplitude equal to each other and a phase difference in 180degrees from each other. Then coupler 720 removes a known component ofreference modulation signal 724. This preparation allows reducing achange amount of an input signal at A/D conversion in the feedbacksystem circuit. As a result, the A/D converter of the feedback systemcircuit does not necessarily to have a wide dynamic range performance.Use of a reference table in this seventh embodiment allows compensatingappropriately distortions created in a transmission system circuit, suchas a power amplifier, having non-linear characteristics which is hard toexpress in a numerical formula.

Further in this embodiment, since the input signal to the referencetable updating section includes a component of transmission digitalorthogonal base-band signal, no changes are needed in an algorithm usedin the reference table updating section of the conventional method. Inthe conventional method, parts of the transmission signal are fed backas a feedback signal, then the feedback signal is orthogonallydemodulated and undergoes A/D conversion to become a digital feedbacksignal. The conventional method compares this feedback signal with anorthogonal modulation signal to be transmitted.

Further, the amplitude control section is prepared to the third datadelaying section, so that a dynamic range of a digital signal to be fedinto the reference table updating section can be controlled.

In the foregoing description, the phase/amplitude control section isdisposed to the signal distributed from the transmission modulationsignal; however, the control section can be disposed to the referencemodulation signal instead.

Exemplary Embodiment 8

The transmission device in accordance with the eighth exemplaryembodiment of the present invention includes amplitude control section826, for controlling the amplitude of a transmission digital orthogonalbase-band signal, in addition to the transmission device of the sixthembodiment. The eighth embodiment is demonstrated hereinafter, but thedescriptions of the same sections as those of the sixth embodiment areomitted, and an operation focused on the different sections from thesixth embodiment are detailed.

FIG. 8 shows a block diagram illustrating the transmission device inaccordance with the eighth embodiment. This transmission devicecomprises the following elements:

-   -   instantaneous power calculator 802;    -   compensation coefficient calculator 804;    -   non-linear distortion compensating section 806;    -   first orthogonal modulator 808;    -   power amplifier 810;    -   directional couplers 812;    -   phase/amplifier control section 815;    -   directional coupler 817;    -   second data delaying section 818;    -   second orthogonal modulator 820;    -   orthogonal demodulator 823;    -   digital adder 825;    -   amplitude control section 826;    -   third data delaying section 828;    -   computation coefficient updating section 831; and    -   first data delaying section 832.

An operation of the transmission device as structured above isdemonstrated hereinafter. Instantaneous power calculator 802 calculatesa magnitude of transmission signal 803 based on transmission digitalorthogonal base-band signal 801. Compensation coefficient calculator 804calculates orthogonal non-linear distortion compensating data 805 by apredetermined computing equation based on the magnitude of transmissionsignal 803.

Non-linear distortion compensating section 806 produces a complexproduct of transmission digital orthogonal base-band signal 801 andnon-linear distortion compensating data 805, and outputs orthogonalbase-band signal 807 undergone the non-linear distortion compensation.First orthogonal modulator 808 orthogonally modulates compensatedbase-band signal 807, then provides signal 807 with D/A conversion, andoutputs analog modulated signal 809.

Power amplifier 810 amplifies analog modulated signal 809 up to anecessary value, and outputs transmission modulation signal 811.Directional coupler 812 outputs the most parts of signal 811 asoutput-transmission modulation signal 813, and distributes the rest astransmission modulation signal 814.

Phase/amplitude control section 815 controls the phase and amplitude ofdistributed transmission modulation signal 814 such that a desirablesignal component of signal 814 has at least a phase different by 180°from that of reference modulation signal 821 created in secondorthogonal modulator 820. Then control section 815 outputs signal 816 ofwhich phase and amplitude are controlled.

Second data delaying section 818 delays transmission digital orthogonalbase-band signal 801 by a predetermined amount. Second orthogonalmodulator 820 orthogonally modulates digital transmission orthogonalbase-band signal 819 delayed by second data delaying section 818, andprovides signal 819 with D/A conversion to output reference modulationsignal 821.

Directional coupler 817 combines signal 816, whose phase and amplitudeare controlled, with reference modulation signal 821, then outputsfeedback signal 822. Orthogonal demodulator 823 provides feedback signal822 with A/D conversion before orthogonally demodulating the signal 822,then outputs feedback digital orthogonal base-band signal 824.

Amplitude control section 826 controls an amplitude of transmissiondigital orthogonal base-band signal 801, and outputs resultant digitalorthogonal base-band signal 827. Third data delaying section 828 outputsdigital orthogonal base-band signal 829 formed by delaying signal 827 bya predetermined amount.

Digital adder 825 adds signal 829 to feedback digital orthogonalbase-band signal 824, and outputs the added feedback digital orthogonalbase-band signal 830.

First data delaying section 830 delays transmission digital orthogonalbase-band signal 801 by a delayed time of the feedback system circuit,and outputs delayed transmission digital orthogonal base-band signal831.

Computation coefficient updating section 831 updates coefficient 834 ofthe computing equation, by which compensation coefficient calculator 804calculates the non-linear distortion compensating data, based on delayedtransmission digital orthogonal base-band signal 833 and added feedbackdigital orthogonal base-band signal 830.

As discussed above, this embodiment shows that the control of a feedbacksignal, i.e. the distributed transmission modulation signal, such thattransmission modulation signal 816 and reference modulation signal 821have an amplitude equal to each other and a phase difference in 180degrees from each other. Then coupler 817 removes a known component ofreference modulation signal 821. This preparation allows reducing achange amount of an input signal at A/D conversion in the feedbacksystem circuit. As a result, the A/D converter of the feedback systemcircuit does not necessarily to have a wide dynamic range performance.

Use of an approximate equation to express non-linear characteristics inthis eighth embodiment allows obtaining non-linear distortioncompensating data with a little amount of memory, and therebycompensating appropriately distortions created in a transmission systemcircuit, such as a power amplifier.

Further in this embodiment, since input signal 830 to the referencetable updating section includes a component of transmission digitalorthogonal base-band signal, no changes are needed in an algorithm usedin the reference table updating section of the conventional method. Inthe conventional method, parts of the transmission signal are fed backas a feedback signal, then the feedback signal is orthogonallydemodulated and undergoes A/D conversion to become a digital feedbacksignal. The conventional method compares this feedback signal with anorthogonal modulation signal to be transmitted.

Further, the amplitude control section is disposed to the third datadelaying section, so that a dynamic range of a digital signal to be fedinto the reference table updating section can be controlled.

In the foregoing description, the phase/amplitude control section isdisposed to the signal distributed from the transmission modulationsignal; however, the control section can be disposed to the referencemodulation signal instead.

In the foregoing demonstration, the non-linear distortion compensatingdata is found by a computing equation; however, the data is not limitedto a specific one as long as the data can be found by processing digitalsignals. For instance, the coefficient can be changed by combiningcomputing equations based on a fixed reference table.

An instantaneous power of the transmission digital orthogonal base-bandsignal is used as an input for finding the non-linear distortioncompensating data; however, the present invention is not limited to thisinput. For instance, an instantaneous amplitude of the foregoing signalor the square of an instantaneous power of the same signal can be used.

Exemplary Embodiment 9

The transmission device in accordance with the ninth exemplaryembodiment of the present invention is equipped with frequency converter918 for changing a center frequency of a signal to be combined indirectional coupler 922. The transmission device in accordance with theninth embodiment is demonstrated, but the descriptions of the samesections as those of the first embodiment are omitted, and an operationdifferent from that of the first embodiment are focused.

FIG. 9 shows a block diagram illustrating the transmission in accordancewith the ninth embodiment. This transmission device comprises thefollowing elements:

-   -   instantaneous power calculator 902;    -   compensation coefficient referencing section 904;    -   reference table 906;    -   non-linear distortion compensating section 909;    -   orthogonal modulator 911;    -   power amplifier 913;    -   directional couplers 915;    -   frequency converter 918;    -   phase/amplifier control section 920;    -   directional coupler 922;    -   second data delaying section 923;    -   second orthogonal modulator 925;    -   orthogonal demodulator 928;    -   reference table updating section 930; and    -   first data delaying section 931.

An operation of the transmission device as structured above isdemonstrated hereinafter. Instantaneous power calculator 902 calculatesa magnitude of transmission signal 903 based on transmission digitalorthogonal base-band signal 901. Compensation coefficient referencingsection 904 produces reference address 905 based on the magnitude oftransmission signal 903, then refers to reference table 906 to be usedfor compensating non-linear distortion, thereby obtaining non-lineardistortion compensating data 907 having characteristics reversal to thenon-linear characteristics of the transmission system. Then referencingsection 904 outputs orthogonal non-linear distortion compensating data908.

Non-linear distortion compensating section 909 produces a complexproduct of base-band signal 901 and orthogonal non-linear distortioncompensating data 908, and outputs orthogonal base-band signal 910undergone the non-linear distortion compensation. First orthogonalmodulator 911 orthogonally modulates compensated base-band signal 910,then provides signal 710 with D/A conversion, and outputs analogmodulated signal 912.

Power amplifier 913 amplifies analog modulated signal 912 up to anecessary value, and outputs transmission modulation signal 914.Directional coupler 915 outputs the most parts of signal 914 asoutput-transmission modulation signal 916, and distributes the rest astransmission modulation signal 917. Frequency converter 918 converts thefrequency of signal 917 before outputting signal 919.

Phase/amplitude control section 920 controls the phase and amplitude ofsignal 919 supplied from frequency converter 918 such that a desirablesignal component of signal 919 has an amplitude equal to that ofreference modulation signal 926 created in second orthogonal modulator925 and has a phase different by 180° from that of signal 926. Thencontrol section 920 outputs signal 921 of which phase and amplitude arecontrolled.

Second data delaying section 923 delays transmission digital orthogonalbase-band signal 901 by a predetermined amount. Second orthogonalmodulator 925 orthogonally modulates digital transmission orthogonalbase-band signal 924 delayed by second data delaying section 923, andprovides signal 924 with D/A conversion to produce reference modulationsignal 926. Directional coupler 922 combines signal 921, whose phase andamplitude are controlled, with reference modulation signal 926, thenoutputs feedback signal 927.

Orthogonal demodulator 928 provides feedback signal 927 with A/Dconversion before orthogonally demodulating the signal 927, then outputsfeedback digital orthogonal base-band signal 929.

First data delaying section 931 delays transmission digital orthogonalbase-band signal 901 by a delayed time of the feedback system circuit,and outputs delayed transmission digital orthogonal base-band signal932.

Reference table updating section 930 updates reference table 906 withnon-linear distortion compensating data 933 based on the delayedtransmission digital orthogonal base-band signal 932 and feedbackdigital orthogonal base-band signal 929.

As discussed above, this embodiment shows that the frequency converterconverts the frequency of the feedback signal, thereby steadily removinga known component of the reference modulation signal from the feedbacksignal that is used for updating the non-linear distortion compensatingdata. As a result, the A/D converter of the feedback system circuit doesnot necessarily to have a wide dynamic range.

In this embodiment, the phase/amplitude control section is disposedafter the frequency converter; however it can be disposed before theconverter, and the control section can be disposed after the secondorthogonal modulator.

In this embodiment, a reference table is disposed; however, instead ofthe reference table, the coefficient of a computing equation can beupdated by calculating the non-linear distortion compensating data withthe computing equation of the compensation coefficient calculator, asdiscussed in the second embodiment.

An instantaneous power of the transmission digital orthogonal base-bandsignal is used as an input for finding the non-linear distortioncompensating data; however, the present invention is not limited to thisinput. For instance, an instantaneous amplitude of the foregoing signalor the square of an instantaneous power of the same signal can be used.

Exemplary Embodiment 10

The transmission device in accordance with the tenth exemplaryembodiment of the present invention includes signal combiner 1022instead of a directional coupler for obtaining a combinatory signal, andcombines a signal at a base-band. The transmission device in accordancewith the tenth embodiment is demonstrated, but the descriptions of thesame sections as those of the first embodiment are omitted, and anoperation different from that of the first embodiment are focused.

FIG. 10 shows a block diagram illustrating the transmission inaccordance with the tenth embodiment. This transmission device comprisesthe following elements:

-   -   instantaneous power calculator 1002;    -   compensation coefficient referencing section 1004;    -   reference table 1006;    -   non-linear distortion compensating section 1009;    -   orthogonal modulator 1011;    -   power amplifier 1013;    -   directional couplers 1015;    -   phase/amplifier control section 1018;    -   orthogonal demodulator 1020;    -   signal combiner 1022;    -   second data delaying section 1023;    -   reference table updating section 1026; and    -   first data delaying section 1027.

An operation of the transmission device as structured above isdemonstrated hereinafter. Instantaneous power calculator 1002 calculatesa magnitude of transmission signal 1003 based on transmission digitalorthogonal base-band signal 1001. Compensation coefficient referencingsection 1004 produces reference address 1005 based on the magnitude oftransmission signal 1003, then refers to reference table 1006 to be usedfor compensating non-linear distortion, thereby obtaining non-lineardistortion compensating data 1007 having characteristics reversal to thenon-linear characteristics of the transmission system for outputtingorthogonal non-linear distortion compensating data 1008.

Non-linear distortion compensating section 1009 produces a complexproduct of base-band signal 1001 and orthogonal non-linear distortioncompensating data 1008, and outputs orthogonal base-band signal 1010undergone the non-linear distortion compensation. First orthogonalmodulator 1011 orthogonally modulates compensated base-band signal 1010,then provides signal 1010 with D/A conversion, and outputs analogmodulated signal 1012.

Power amplifier 1013 amplifies analog modulated signal 1012 up to anecessary value, and outputs transmission modulation signal 1014.Directional coupler 1015 outputs the most parts of signal 1014 asoutput-transmission modulation signal 1016, and distributes the rest astransmission modulation signal 1017.

Phase/amplitude control section 1018 controls the phase and amplitude ofsignal 1017 such a desirable signal component of signal 1017 has anamplitude equal to that of distributed reference base-band signal 1024,which is described later, and has a phase different by 180° from that ofsignal 1024. Then control section 1018 outputs signal 1019 of whichphase and amplitude are controlled. Orthogonal demodulator 1020orthogonally demodulates signal 1019 and outputs orthogonal base-bandsignal 1021.

Second data delaying section 1023 delays transmission digital orthogonalbase-band signal 1001 by a predetermined amount, then provides signal1001 with D/A conversion, and outputs delayed reference base-band signal1024. Signal combiner 1022 combines orthogonal base-band signal 1021 andreference base-band signal 1024, and provides the resultant signal withA/D conversion, so that feedback digital orthogonal base-band signal1025 is obtainable.

First data delaying section 1027 delays transmission digital orthogonalbase-band signal 1001 by a delayed time of the feedback system circuit,and outputs delayed transmission digital orthogonal base-band signal1028.

Reference table updating section 1026 updates reference table 1006 withnon-linear distortion compensating data 1029 based on the delayedtransmission digital orthogonal base-band signal 1028 and feedbackdigital orthogonal base-band signal 1025.

As discussed above, this embodiment shows that a known component of thereference modulation signal can be removed at a base-band from thefeedback signal that is used for updating the non-linear distortioncompensating data. As a result, the A/D converter of the feedback systemcircuit does not necessarily to have a wide dynamic range performance.

In this embodiment, the phase/amplitude control section is disposed to asignal distributed from the transmission modulation signal; however, thecontrol section can be disposed to the reference base-band signalinstead.

In this embodiment, a reference table is disposed; however, instead ofthe reference table, the coefficient of a computing equation can beupdated by calculating the non-linear distortion compensating data withthe computing equation of the compensation coefficient calculator, asdiscussed in the second embodiment.

An instantaneous power of the transmission digital orthogonal base-bandsignal is used as an input for finding the non-linear distortioncompensating data; however, the present invention is not limited to thisinput. For instance, an instantaneous amplitude of the foregoing signalor the square of an instantaneous power of the same signal can be used.

In the embodiments 1-9, orthogonal demodulator 126, 223, 326, 423, 526,623, 726, 823, and 928 are demonstrated after A/D conversion; however,the A/D conversion can be carried out after the orthogonal demodulation.The first orthogonal modulator in every embodiment is carried out beforeD/A conversion; however, the D/A conversion can be carried out beforethe orthogonal modulation.

Industrial Applicability

The transmission device of the present invention includes non-lineardistortion compensating function which allows the A/D converter of thefeedback system circuit not necessarily to have a wide dynamic rangeperformance. This transmission device can be used in communicationapparatuses of radio communication systems which adopt a digitalmodulation method, and is useful for compensating non-linear distortionscreated in an amplifier of the transmission system.

1. A transmission device comprising: a non-linear distortioncompensating section for compensating non-linear distortion of anorthogonal base-band signal digitally modulated by using non-lineardistortion compensating data which compensates the non-lineardistortion; a first orthogonal modulator for orthogonally modulating theorthogonal base-band signal undergone the non-linear distortioncompensation; a modulation signal distributor for distributing amodulation signal formed by amplifying a signal orthogonally modulatedby the first orthogonal modulator; a phase/amplitude control section forcontrolling a phase and an amplitude of at least one of a distributedsignal distributed by the modulation signal distributor and a referencesignal based on the orthogonal base-band signal; a signal combiner forcombining a combinatory signal based on the distributed signal and thereference signal at least one of which signals phase and amplitude arecontrolled by the phase/amplitude control section; and a reference tableupdating section for updating the non-linear distortion compensatingdata based on the combinatory signal combined by the signal combiner andundergone analog-digital conversion and the orthogonal base-band signal.2. The transmission device of claim 1, wherein the phase/amplifiercontrol section controls a phase and an amplitude of the distributedsignal, and the reference signal is generated by a second orthogonalmodulator which generates a reference modulation signal by orthogonallymodulating the orthogonal base-band signal, wherein the reference tableupdating section updates the non-linear distortion compensating data byusing the orthogonal base-band signal and one of a demodulated signalobtained by an orthogonal demodulator which orthogonally demodulates thecombinatory signal undergone the analog-digital conversion beforeoutputting and a demodulated signal obtained by an orthogonaldemodulator which provides the combinatory signal with analog-digitalconversion before outputting.
 3. The transmission device of claim 2,wherein at least one of the distributed signal supplied to thephase/amplitude control section from the modulation signal distributorand a signal supplied to the signal combiner from the second orthogonalmodulator has undergone a frequency conversion.
 4. The transmissiondevice of claim 3 further comprising a reference table for storing thenon-linear distortion compensating data.
 5. The transmission device ofclaim 3, wherein the device includes, instead of the reference tableupdating section, a compensation coefficient calculator for calculatingthe non-linear distortion compensating data with a computing equationand a computing coefficient updating section for updating a coefficientof the computing equation.
 6. The transmission device of claim 2 furthercomprising a reference table for storing the non-linear distortioncompensating data.
 7. The transmission device of claim 2, wherein thedevice includes, instead of the reference table updating section, acompensation coefficient calculator for calculating the non-lineardistortion compensating data with a computing equation and a computingcoefficient updating section for updating a coefficient of the computingequation.
 8. The transmission device of claim 1, wherein the referencesignal is created by a second orthogonal modulator which generates areference modulation signal by orthogonally modulating the orthogonalbase-band signal, wherein the phase/amplitude control section controls aphase and an amplitude of the reference modulation signal; wherein thereference table updating section updates the non-linear distortioncompensating data by using the orthogonal base-band signal and one of ademodulated signal obtained by an orthogonal demodulator whichorthogonally demodulates the combinatory signal undergone theanalog-digital conversion and a demodulated signal obtained by anorthogonal demodulator which provides the combinatory signal withanalog-digital conversion before outputting.
 9. The transmission deviceof claim 8, wherein at least one of a distributed signal supplied to thephase/amplitude control section from the modulation signal distributor,a signal supplied from the phase/amplitude control section to the signalcombiner, and a signal supplied from the second orthogonal modulator tothe signal combiner has undergone a frequency conversion.
 10. Thetransmission device of claim 9 further comprising a reference table forstoring the non-linear distortion compensating data.
 11. Thetransmission device of claim 9, wherein the device includes, instead ofthe reference table updating section, a compensation coefficientcalculator for calculating the non-linear distortion compensating datawith a computing equation and a computing coefficient updating sectionfor updating a coefficient of the computing equation.
 12. Thetransmission device of claim 8 further comprising a reference table forstoring the non-linear distortion compensating data.
 13. Thetransmission device of claim 8, wherein the device includes, instead ofthe reference table updating section, a compensation coefficientcalculator for calculating the non-linear distortion compensating datawith a computing equation and a computing coefficient updating sectionfor updating a coefficient of the computing equation.
 14. Thetransmission device of claim 1 further comprising: an orthogonaldemodulator for one of orthogonally demodulating the combinatory signalundergone the analog-digital conversion, then outputting a resultantsignal and converting the combinatory signal undergone orthogonaldemodulation, then outputting a resultant signal; and an adding circuitfor adding the orthogonal base-band signal and the demodulated signalsupplied from the orthogonal demodulator, wherein the reference tableupdating section updates the non-linear distortion compensating data byusing an output from the adding circuit and the orthogonal base-bandsignal.
 15. The transmission device of claim 14, wherein the orthogonalbase-band signal to be added to the adding circuit is controlled itsamplitude.
 16. The transmission device of claim 1, wherein the signalcombiner combines the distributed signal orthogonally demodulated andthe reference signal into a combinatory signal.